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Investigating the affect of Copper Sulphate on Liver.

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Title: Inhibitory of copper Sulphate on enzyme catalase found in Liver Aims: Investigating the affect of Copper Sulphate on Liver. Hypothesis: Catalase is a red crystalline enzyme that consists of a protein complex with a haem groups in the centre. Catalase catalyses the decomposition of hydrogen peroxide into water and oxygen: 2H2O2 2H2O + O2 An enzyme inhibitor is a substance that slows down the rate at which an enzyme-catalysed reaction takes place. Many enzyme inhibitors work by binding with the enzyme, with the result that the enzyme can no longer bind with its substrate Some inhibitors have shapes rather like the enzyme's normal substrate molecule, allowing them to bind at the active site of the enzyme. They are called active site-directed inhibitors. If there is an inhibitor molecule in the active site, the substrate cannot bind there. Some active site-directed inhibitors bind permanently to the active site, so that they permanently inactivate the enzyme. While the inhibitor is out of the active site, it is possible for a substrate molecule to slot in, so the inhibitor will not completely stop the reaction, just slow it down. The inhibitor and the substrate are competing for the active site, so these inhibitors are sometimes called competitive inhibitors. The chances of a substrate molecule getting into the active site depend on: > The relative concentrations of substrate and inhibitor - the more substrate molecules there are compared to inhibitor molecules; the more likely it is that a substrate rather than an inhibitor will bind with the enzyme's active site. > How long the inhibitor stays attached to the enzyme before moving away - the shorter the inhibitor-enzyme complex lasts, the more chance the substrate has to bind with the active site, and the less the inhibition of the reaction. ...read more.


Quickly connect the rubber bung, which is connected to the tubing, to the test tube. XII. From the Syringe measure the gas given off, record it in a table XIII. Repeat the first 12 steps, 6 times each time changing step 5 to 0.3,05,07,09 and 1 mole. To get 0.3 mole add 3cm3 of copper sulphate with 7cm3 of distilled Water and so on. XIV. Repeat step 1 to 13 at least three times (time dependent) so that an average can be obtained. Repeating the experiments several times will help to produce better and more accurate results, as any inaccuracies in one experiment should be compensated for by the other experiments. XV. Create a table of the results, from these results, a graph can be plotted with concentration on the x-axis and the volume of gas released on the y-axis. Preliminary Measurements: In my preliminary work I found that as you increase the concentration of hydrogen peroxide the rate of reaction also increase this is because there is more hydrogen peroxide molecule to combine with the enzyme. In this experiment the hydrogen peroxide stays constant, the reason why I choose 5 cm3 of hydrogen peroxide is because 10 cm3 of H202 would be too much and we did not have enough liver as well so therefore 5 cm3 of H202 was reasonable amount of H202. Also the mass of the liver in my experiment stays constant, I decided to choose 1Kg; the reason for this is because in my preliminary work I found out that the more the mass of liver the greater the enzyme present and if there are more of enzyme present; then the reaction would take quite long time. ...read more.


> Repeat the experiment more times There are numbers of other further experiment we could do: > Do the same experiment but in the end add more hydrogen peroxide to see how much amount of oxygen is given off, if more then last reading given off that means that the inhibitor is competitive reversible. > We could find out where in enzyme does copper sulphate combine with the enzyme does it combine at the active site or elsewhere on the enzyme. > The temperature remained constant at room temperature we could have changed the temperature see what exactly what happens To find percentage error: I measured the movement of the syringe to 3 significant figures. So the range can be + 0.05 or -0.05 the results. To find the percentage error we add the result or minus it by {(0.05/the result)and timing it by 100}. This is going to give us a positive percentage error and negative percentage error. Experiment Average(cm) Percentage error(%) PE + Average PE-Average 1 14.80 15.13 29.93 0.33 2 11.50 11.92 23.42 0.42 3 8.60 9.16 17.76 0.56 4 7.40 8.11 15.51 0.71 5 1.60 4.10 5.70 2.50 Key PE- percentage error The range between pink and yellow line shows where the results could lie, it shows the maximum and minimum point of the results. If you analyse the graph we can see that the line of best fit for the average is slightly in the middle of positive and negative percentage error line of best fit. Which means that the results are accurate as percentage error is not that great. ...read more.

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